The present invention relates to a support arrangement for supporting a tubular member. More particularly, the present invention relates to a support arrangement in the form of a two-piece clamping member for engaging and holding a tubular member, such as a fluid-carrying conduit, in a desired position against the effects of vibratory forces to which the tubular member is subjected.
Cylindrical members, such as support rods, or tubular conduits for carrying fluids, are often supported relative to a support surface or another component so that they are in a predetermined position, and also so that they are restrained from vibrating excessively, in order to avoid fatigue failure of the cylindrical member. Fluid-carrying conduits are generally found on various types of machinery for carrying pressurized gases, such as pressurized air, or pressurized liquids, such as hydraulic fluid. Because operating machinery generally often involves some degree of vibration, such conduits are frequently subjected to alternating vibratory forces that can cause excessive vibratory movement of the conduits. The vibratory movements must be minimized, or at least controlled, to avoid a resonant condition and also to avoid vibration-induced fatigue failure of the conduits.
Various supporting arrangements are known for supporting rods or conduits. Different forms of clamps have been devised to engage the rod or conduit and to hold it substantially steady relative to a surface of the equipment with which the conduit is associated. Generally, increased resistance to vibration-induced fatigue failure can be provided by increasing the size or weight of the clamp. However, in certain applications, such as in aircraft engines, the weight of the clamping arrangement must be minimized, while simultaneously providing the desired rigidity, the desired resistance to fatigue failure of the clamped member and of the clamp itself, and the desired ability simultaneously to withstand both the dynamic loads and the high temperature environment to which such elements are subjected during the operation of aircraft engines.
One form of tubing clamp that has been utilized on aircraft gas turbine engines includes two generally U-shaped clamp halves that are hingedly connected together at respective first ends thereof. The clamp halves can be opened to allow a tube to be positioned therebetween, and then pivoted together to enclose and surround the tube. Each such clamp half typically includes a generally semicircular recess to surround a portion of the outer surface the tube. A fastener, such as a threaded bolt, extends through openings formed in the ends of the tube clamp halves that are opposite to the hinged connection so that the bolt can be inserted through the openings. A connecting nut is threaded onto the bolt for drawing together the two clamp halves around the tube. The fastener typically also extends through an engine-mounted bracket for holding the tube relative to the outer surface of the engine casing.
The weight of the clamp structure can be minimized by forming it from a light weight metal, such as an aluminum alloy. But light weight metals often lack the necessary fatigue strength to withstand vibratory loads to thereby resist premature failure due to metal fatigue. Heavier metals, although generally more fatigue resistant, add weight to the structure, which is undesirable in an aircraft engine.
In addition to the fatigue aspects of known, hinged tubing clamp designs, tubing clamps that do not have a hinged connection can have tendency to rotate relative to each other during installation of a connecting bolt. Such relative rotation can cause the two parts of the clamp to be angularly skewed and misaligned relative to each other, which can cause the clamp members not to fully engage the conduit outer surface. In that condition edges of the clamp can bear against the outer surface of the conduit and result in stress concentrations within the conduit. Consequently, vibratory forces can cause the clamp edges to create irregular contact of the conduit outer surface over time and can lead to wear failure of the tubing.